The conventional stroller generally includes two wheel devices respectively installed at the front and the rear parts of the stroller, a main frame, a collapsing mechanism, and a handlebar for controlling the stroller to go forward. Most of strollers respectively have a wheel at right side and left side in the front and rear wheel devices to make the stroller respectively has a wheel at four corners of the bottom of the stroller. Besides this kind of the four-wheeled stroller, there is a three-wheeled stroller which is characterized in that the front wheel device only has a wheel and the rear wheel device respectively has a wheel at the right and left sides. The significant advantage of the three-wheeled stroller is the single front wheel is easier and more smooth in the respect of changing direction than that of the four-wheeled stroller and adapted to move faster. For example, the user goes jogging or rapidly walking with the stroller for taking exercise.
Because one major object of the three-wheeled stroller is to easily and smoothly change directions and rapidly move, the wheel having a large diameter is more competent to the requirements. The wheel with the large diameter has better effects on changing directions and absorbing the jolt due to the rough road. However, the large wheel increases the volume of the stroller, especially in the state of collapsing, which is disadvantageous for accommodation and transportation. Therefore, in certain situations, the user desires the wheel to be easily and quickly released, particularly for the large front wheel device.
What is more important is although the three-wheeled stroller has the feature of easily changing directions, in certain situations, the user however must fixed the front wheel device at a predetermined direction to prevent it from unnecessarily changing the march direction. Therefore, it is necessary for front wheel device to have a direction-fixed means reliable and easy to be operated.